Hatches provide access to a generally sealed environment such as areas of a military vehicle. Such hatches must be constructed to meet the same structural requirements as the surrounding structure. Furthermore, the hatch must maintain the integrity of the sealed environment when locked down.
The structural and weight requirements for a hatch frequently make them difficult to open. One of the main purposes of a hatch is to facilitate the movement of military personal, while providing the same level of protection as the rest of the vehicle structure. Depending upon the vehicle or embodiment, any particular hatch may include armor. Additional “top-attack” armor is commonly used to enhance protection when a vehicle is within a particularly high threat area. These survivability requirements drastically increase the weight of the hatch adding to the difficulty of operating the hatch.
With respect to armored vehicles, the driver's hatch has distinct requirements for operational performance as well as survivability. The driver must be able to have clear visibility to drive the armored vehicle. In many situations the driver will choose to have his head extend outside the hatch frame. In combat operations, however, the driver needs protection, and that requires a hatch that shields the driver.
Thus there is a need for a hatch that allows for operational performance and survivability. A hatch should be relatively easy to function, while remaining reliable. In a military vehicle, reliability must be maintained through rigorous and damaging conditions. The hatch of a military vehicle should accommodate the addition of armor. The steps needed to open and close the hatch portal should be minimal, taking into consideration the amount of force and time needed to operate the hatch during emergencies. Further, there is a need in armored vehicles for a hatch that allows the driver to remain protected while still performing the required mission.